To easily retrieve the service position of a server device.

A generation part 26 of a composite unit 20 generates service position information including a network address and encrypted specific information for self-identification. A printing part 23 adds the service position information to a raster image to be printed, and prints it on a sheet 16. A transmitting part 46 of the composite unit 40 transmits a connection request including the service position information and its own network address extracted from a sheet 16 read by a reading part 43 to the composite unit 20. A judging part 28 of the composite unit 20 verifies the specific information based on specific information included in the connection request received by a receiving part 27, and registers the network address of the composite unit 40 in a service position information storage part 24. Afterwards, a permission returning part 29 returns a connection permission response to the composite unit 40. A registering part 48 of the composite unit 40 confirms the reception of the connection permission response by a receiving part 47, and then registers the network address of the composite unit 20 in a service position information storage part 45.